/Engine/Source/Runtime/GeometryCore/Public/Util/IndexSetDecompositions.h
FArrayIndexSetsDecompositionrepresents a decomposition of an integer index set into subsets, which are stored as arrays (ie this is just an array of arrays, where each sub-array has a unique integer identifier)
class FArrayIndexSetsDecomposition
TArray< int32 >
AllSetIDs
int32
IDCounter
TMap< int32,FI...
SetIdentifierMap
TIndirectArray<...
Sets